Brand Newbie here - working on a Land Speed Project (1.5L or less diesel).

[R.O.R-2.0]

I'm curious about the glow plug deletion.  This is something new to me.  I realize that removing the GP's would reduce compression a bit, but would it really be worthwhile to remove the GP's and just fill the holes with some plugs?

It seems to me that leaving the GP's in, for easier starting, would outweigh any potential performance benefit to be had by lowering the compression ratio even further.

Like I said, this is all new to me, so please feel free to set me straight.

Steve.

if you delete the plugs, you wont blow a plug apart from having to use ether to start it..

the big tractor puller diesels use LOTS to start their engines, and keep them running long enough to sustain life..

i imagine it will be such low compression that ether will be required..

[MJF]

Umm, I don't see the reason of lowering compression? And removing glow plugs? That sounds just stupid with idis. Stock compression ratio is more than ok with your power goals. You can have engine that behaves and starts like stock engine and will make 150hp.

[R.O.R-2.0]

Umm, I don't see the reason of lowering compression? And removing glow plugs? That sounds just stupid with idis. Stock compression ratio is more than ok with your power goals. You can have engine that behaves and starts like stock engine and will make 150hp.

thats what i tried telling him! stock compression is fine up to like 200hp, or more..

all lower compression is going to do, is make it harder for you to reach your goal.. you will need more boost to make the same power.

only reason i suggested removing the glowplugs is because its going to be such low compression that it will basically require ether to start, and ether blows the tips off glow plugs.. so if i cant talk him out of lowering the compression, then im going to suggest what he can do to do it safely..

my engine is a STOCK 1.6D long block, and i bet im pretty close to the 150hp mark. i know i will be 150hp once i install my 10mm pump

[theman53]

I think once again you are traveling into a trail and error. If you could have a shop machine you something that looked like a glowplug only was one solid chunk of steel, then you wouldn't loose any compression ratio. I agree that lowering it further would be a bad deal probably. It would be easier to leave the glowplugs in there and run them from a seliniod  a la vince waldon style. You can run them on a push button toggle while cranking or not for as long as you need.
After having a precup fall into my IDI I really wouldn't do ether, even without a functioning glow plug and lower compression.

[theman53]

Here's the link to vw's official 1.5l white paper.
http://home.comcast.net/~jakeru/15dsae.pdf
It mentions that a compression ratio of 16-1 to 18-1 is ideal for best power and fuel consumption even for an idi engine but starting and idling becomes a problem.  Lots of good info.

I don't think he is lowering the CR for performance. I think he is only lowering it as that is what the aaz head will do to it. Also, if he will be at 19:1 as someone stated then he is above the numbers listed so he maybe ok. It might start a touch hard and smoke some at idle, but it will start and run well hopefully.

[Jetmugg]

Exactly as TheMan stated.  The reduction in CR would be only as a result of using the better-flowing AAZ head on the 1.6 block, along with the 1.5 rotating assembly.  The lower CR is not intentional, it's a side effect of the necessary combination of parts.  There is no readily available combination of rods and pistons that would maintain the 23.5:1 compression ratio for a 1.5L rotating assembly when combined with the 1.9L AAZ head.

Around-town driveability is not a concern. 

If I build it and it will start with the use of GP's, then there would be no need to delete them.  (this is the trial and error area - as far as I can tell, there are no 1.5L "Franken" diesels with the 1.9L heads running around currently.

A nice big juicy turbo will have to be part of the recipe, along with a properly sized intercooler.

In order to race in the class that I want to race in, the engine must be a nominal 1.5L or less.

Part of the allure of LSR racing is also the kooky engine combinations that are used....

Steve.

[R.O.R-2.0]

Exactly as TheMan stated.  The reduction in CR would be only as a result of using the better-flowing AAZ head on the 1.6 block, along with the 1.5 rotating assembly.  The lower CR is not intentional, it's a side effect of the necessary combination of parts.  There is no readily available combination of rods and pistons that would maintain the 23.5:1 compression ratio for a 1.5L rotating assembly when combined with the 1.9L AAZ head.

Around-town driveability is not a concern. 

If I build it and it will start with the use of GP's, then there would be no need to delete them.  (this is the trial and error area - as far as I can tell, there are no 1.5L "Franken" diesels with the 1.9L heads running around currently.

A nice big juicy turbo will have to be part of the recipe, along with a properly sized intercooler.

In order to race in the class that I want to race in, the engine must be a nominal 1.5L or less.

Part of the allure of LSR racing is also the kooky engine combinations that are used....

Steve.

i would use the 1.6 head still.. its going to be an all around better engine.

quite a few of us have debated the 1.5/6/9 hybrid, and we scrapped the idea because sauerkraut built one, and it sucked..

[Jetmugg]

I've been searching the archives for any info on Saurkraut's 1.5/1.6/1.9 engine.  I have found several threads where he was trying to figure out the right combination of parts (1.9 rods, etc), but I haven't been able to find a thread or post where the 1.5/1.6/1.9 engine has actually been assembled.

If you can point me to a thread where someone has this engine setup built and running, that would be great.

What kind of problems was Saurkraut (I assume he doesn't post here anymore) having?  Hard starts?  Smoky low-rpm operation?

I just can't find any documentation to show that Saurkraut successfully had a 1.5/1.6/1.9 engine built and running.  I'd like to read more about it, but can't find it using the search function.  Maybe I just haven't found it yet.


Steve.

[rabbid79]

The lower CR is not intentional, it's a side effect of the necessary combination of parts.  There is no readily available combination of rods and pistons that would maintain the 23.5:1 compression ratio for a 1.5L rotating assembly when combined with the 1.9L AAZ head.

Actually, there's no combination of custom parts that would give you a 23.5:1 compression ratio with an AAZ head and a 1.5L bottom end.  The swirl chamber volume in the AAZ head was matched to the 1.9 liters of displacement of the engine AAZ to give it the 23:1 ratio it has.  Since your displacement will be a lot less, so will your compression ratio.

I, for one, am an advocate of running the lowest realistic compression ratio possible that will still get the engine to fire and idle.  That 23.5:1 compression ratio is your friend when you're trying to crank an engine in the cold.  But once the engine is warmed up, and after you add 20-30 lbs of boost, that compression ratio isn't going to do anything good to your engine.

If you can do it without glow plugs, I'd scrap them.  In a high horsepower/high endurance engine, they're just a liability.  I've been to the races at Bonneville, and it's plenty warm - like 90's.  With a good starter, a good battery, possibly a block heater beforehand, and the ingenstion of some hot air, I'll bet it would start just fine.  In fact, I'll supply you a portable generator to use to run a block heater and hot air gun if that's the way you decide to go.  I'm in Utah and can help if you need some help.

[burn_your_money]

How is the 1.016 - 1.523 Liters measured? Is it only the swept volume? It would be a shame if the larger head bumper you into the G class and you only got a speed of 120 MPH

[R.O.R-2.0]

How is the 1.016 - 1.523 Liters measured? Is it only the swept volume? It would be a shame if the larger head bumper you into the G class and you only got a speed of 120 MPH

larger head adds displacement doesnt it? i never really thought about it before..

[Alcaid]

How is the 1.016 - 1.523 Liters measured? Is it only the swept volume? It would be a shame if the larger head bumper you into the G class and you only got a speed of 120 MPH

larger head adds displacement doesnt it? i never really thought about it before..

NO! Displacement is the swept volume of the pistons.

[VW Smokr]

The word is "displacement". as in something (a volume of air inside the cylinder) is being displaced with a slug of aluminum. Head volume won't be entering into the displacement equation as long as you're still running 1.5L crank & pistons, since the minor increase in "combustion chamber" volume won't be displaced by any piston parts (hopefully). Still 1471cc + still class legal.

J.R.
SoCal

[RadoTD]

I don't know what you guys (MJF/ROR) have against lowering compression? It's simple math that you can make more power on lower compression before having any mechanical failure (head gasket/breaking rods/breaking head studs etc). He doesn't need to cold start it every morning, I don't see how 18:1 would be such a problem?

Everything I've read says that diesels are more mechanically efficient as you get towards 16:1, but lets ignore that for a second... if you can make 150whp at 30psi and 23:1, drop to 18:1 and you can do 40psi and make gobs more power. 1.6 head and no glow plugs will probably bring you to around 18:1

I'm not saying it's required for 150whp, by why not drop it and make 180whp?

[MJF]

I don't know what you guys (MJF/ROR) have against lowering compression? It's simple math that you can make more power on lower compression before having any mechanical failure (head gasket/breaking rods/breaking head studs etc).

I like engines that work right, smoky hard starting one is not like that. 150whp (or 180whp) doesn't need lowering compression ratio.